The invention discloses a harmless comprehensive utilization method of chromium slag, belonging to treatment and comprehensive utilization of chromium slag technical field, which utilizes the high temperature sintering method of band sintering machine. The invention is characterized in that (1) chromium slag, iron fine powder ore, rich iron ore, converter dust and mill scale, or chromium slag, pyrite cinder and scrap iron are matched reasonably, (2) the proper basic flux and fuel (coke powder, anthracite powder) are added and mixed evenly, and (3) the ignition sintering in the band sintering equipment is processed. The harmless comprehensive utilization method of chromium slag has the advantages of adopting band sintering machine, utilizing sintering craft, adopting chromium slag as basic flux, rational mixture of chromium slag and iron-bearing material and fuel, sintering agglomeration by band sintering machine, making strong reducing atmosphere, making the hexavalent chromium in the chromium slag react with the reducing agent of carbon and carbon monoxide completely and reduced to trivalent chromium in the half process to realize the harmless comprehensive utilization, reducing hexavalent chromium to trivalent chromium in the sintering high temperature and high temperature process material, making the trivalent chromium in the smelting-used self-melting sintered ore, realizing the comprehensive utilization art of chromium slag, no secondary pollution, fast treatment speed, and low cost.